If you're new to the software profession, you may find that you have a lot more money coming in than you did previously, and you probably want to spend some of it on things you couldn't afford before.
Resist this urge. Once you've accustomed yourself to a higher standard of living you'll have a hard time going back—we call this lifestyle inflation. If you've managed to live without something this far, it probably wasn't that important.
If you're comfortable living with roommates, driving an older car, or dressing solely in free swag t-shirts, continue to do so!
An underappreciated advantage of working as an engineer is that you don't have to project the appearance of material success unless you want to. A lawyer needs a new car, a closet full of tailored clothes, and an expensive watch if she wants to convince clients that she's reputable. Engineers aren't expected to conspicuously consume luxury goods, so we have the option of putting that money to better use.